Actuator for elastic diaphragm switch keyboard

ABSTRACT

An actuator sheet carries clusters of switch actuating projections aligned with openings which receive deflectable contacts of an array of diaphragm switches. Intersecting ribs are carried on the same side of the actuator sheet as the switch actuating projections, to define isolation zones for the projections corresponding directly to the individual key areas of the keyboard. Integral, raised pressure pads for each key area are formed on the upper surface of the actuator sheet to enhance even pressure distribution over the pertinent switch contact area.

United States Patent Brooks et al.

[54] ACTUATOR FOR ELASTIC DIAPHRAGM SWITCH KEYBOARD [72] Inventors:Kenneth A. Brooks, Cary; Lawrence L. Johnson; James A. Mathewson, bothof Raleigh, all of NC.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: June 30, 1970 [21] Appl. No.: 51,284

[52] US. Cl. ..197/98, 200/5,200/46,

200/159, 235/145 [5 l] Int. Cl. B4lj 5/08 Field of Search ..197/98, 102,103, 104; 35/5, 35/6; 340/337; 84/326, 423,445, 446, 447,

[ References Cited UNITED STATES PATENTS,

2/1964 Cornell ..'..200/-5 E 1451 Se t. 26, 1972 Krakinowski ..200/463,382,338 5/1968 Arseneault et al. ....200/l59 B 3,551,616 12/1970Juliusburger et al. ..200/46 3,560,675 2/1971 Krakinowski et al...200/46 3,584,162 6/1971 Krakinowski ..200/5 A Primary Examiner-ErnestT. Wright, Jr. Attorney-Hanifin and Jancin and Laumann 5 ABSTRACT Anactuator sheet carries clusters of switch actuating projections alignedwith openings which receive deflectable contacts of an array ofdiaphragm switches. lntersecting ribs are carried on the same side ofthe actuator sheet as the switch actuating projections, to defineisolation zones for the projections corresponding directly to theindividual key areas of the keyboard. Integral, raised pressure pads foreach key area are formed on the upper surface of the actuator sheet toenhance even pressure distribution over the pertinent switch contactarea.

6 Claims, 5 Drawing Figures PATENTEDsEm I972 3 693. 7 7 5 SHEET 1 0F 2 I1 1 17 I N FIG.| {a PRIOR ART E 1 Te 22 .E 23 5\\ \\\\\\T v 4' A 24?\\\\\\N .\\\\\\m r\ \\\Y}28 \\T\\\\\1\\\\\1 1M PRIOR ART HQ 2 T 3INVENTORS W KENNETH ALONZO BROOKS LAWRENCE LEE JOHNSON JAMES ALFREDNATREwsoN BY ZQAJW ATTORNEYS ACTUATOR FOR ELASTIC DIAPHRAGM SWITCHKEYBOARD BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to keyboards for providing input of data to electricalapparatus and more particularly to keyboards incorporating elasticdiaphragm switches and the like. I

2. Description of the Prior Art A manual keyboard employing anintegrated keying mechanism has previously been employed in an elasticdiaphragm switch array incorporated within the keyboard. This type ofstructure has provided a simplified keyboard at reduced cost whileproviding a variably responsive mechanism in terms of manual force andpressure required for operation. Additionally, this structure providespretravel, overtravel, variable touch and the effect of a" keystopto'simulate I the'feel of conventional keyboard. operated apparatus,

such as typewriters. These prior art devices will, for the sake ofclarity, be discussed in. greater detail in'the specification whichfollows to more clearlypoint out the differences which characterize thepresent invention. f

SUMMARY OF THE'INVENTION The present invention is directed to animproved elastic diaphragm switch assembly which includes a regulararray of deflectable diaphragm switch contacts and an elastomeric sheetoverlying the array of contacts and which sheet carries a plurality ofprojections depending therefrom in registration with the contacts forselectively actuating the same. In particular, the elastomeric actuatorsheet carries a series' of intersecting, straight-line ribs on the sameside of the sheet as the rigid projections to define individual,rectangular isolation zones for the projections, which zones correspondin number and position to theunderlying array of switch contacts. Thisassures prevention of crosstalk or interference problems betweenadjacent switches when a single key is depressed.

In addition, the present invention is directed to the same elastomericsheet being provided with raised pressure pads corresponding to each keyposition of the keyboard on the surface facing the soft button carriedinternally within the opening of the rigid frame underlying the keyboardkeys. The raised pressure pads provide even pressure distribution overthe pertinent contact area when a key is depressed and allow-relaxationof the tolerance requirements for the soft buttons since a variation inpressure pad tolerance will not be felt by any change in switchactuation pressure. Further, the provision of the intersecting straightribs allows the entire actuator sheet to lie flat on the elasticdiaphragm switch sheet, insuring uniform travel of the keys duringdepression of the same and enhancing uniform alignment of the actuatorprojection with the deflectable switch contact of the elastic diaphragm.

BRIEF DESCRIPTION OF THE DRAWING FIG. ,1. is a vertical section of anintegrated keyboard incorporating an array of elastic diaphragm switchesof prior art design;

FIG. 2 is a top plan view, partially broken away, of a keyboard shown inFIG. 1;

FIG. 3 illustrates an alternative prior art design; FIG. 4 is a bottomplan view of a portion of the improved actuator sheet of the presentinvention as applied to an integrated keyboard similar to that of FIGS.

FIG. 5 is a vertical section of a modified manual keyboard similar tothat of FIG. 1 but incorporating the improved actuator sheet of thepresent invention.

Referring to FIGS. 1 and 2, one form of a prior integrated keyingmechanism constituting a manual keyboard which is presently in use isillustrated. It employs a polyurethane elastomer nomenclature sheet 10which defines the keyboard of the assembly and includes soft flexiblekeys 11 which, upon depression, cause soft elastomer buttons 16 to forceprotrusions 21 of an actuator sheet 20 to operate selected diaphragmswitches in array 28. Contacts 24 are carried by the elastic diaphragm23, while contacts 27 are carried on a rigid sheet 30 supported by base29. Separator sheet 25 of insulative material, normally keeps contacts24 and 27 apart, but apertures 26 in sheet 25 allow the contacts toclose under pressure.

In greater detail, the flexible keys 11 may carry visible indiciaidentifying the same to allow operator-selector depression as evidencedin FIG. 2. Lying below the keyboard sheet 10 is a protective sheet 14,which also may be formed of an elastomer, which serves as a dust coverfor sealing the actuating mechanism below from the environment andfurther facilitating manipulation of sheet 10. The protective sheet 14is supported by a rigid frame member 15 formed of metal or the like andhaving circular or square holes 17 aligned concentrically with keys 11.Keys 11 may thus be depressed centrally due to the holes or openings 17.Within the same holes, and underlying the protective sheet 14, are thekey buttons 16 formed of a soft elastomer and molded integrally in a pad18. The elastomers preferably are closed-pore cellular neoprene rubberwith low compressive modulus.

Below the pad 18 is an actuator sheet 20 comprised, preferably, of amolded neoprene rubber or elastomer and having thereon a plurality ofclusters of truncated cone-shaped protrusions or stops 22 and centralprotrusion 21 in axial alignment with hole 17 and key 11. The four outerprotrusions or stops 22 are of similar length and are slightly shorterthan and are circumprotrusions lie generally within the area of theindividual keys 11. The outer protrusions 22 are rectangularly disposedand spaced from the central protrusion 21, however, they may becircularly disposed instead. Preferably, the central protrusion 21 isabout 6 to 10 mils longer than the outer protrusions 22 which in turnare approximately one eighth inch in length. The central protrusion 21,when depressed, moves the contact 24 into contact with a contact 27 fora given element of switch array 28.

The combination of the very soft key pad 16 and the actuator sheet 20,which is of medium hardness rubber, provides a relatively long keyingstroke with pretravel and overtravel. A soft key pad 16 and the flexiblekeys 11 provide a combination of actuating elements with a low springconstant and a long stroke. These latter characteristics are controlledby the stiffness of key pad 16 and keys 11. Of importance is theprovision of the discrete projections 22 in a uniform spaced patternabout the central projection 21 since these projections concentrate theactuating force on a given switch within the array 28. Because of theoutside projections 22, the actuating force remains constant over thesurface of each of the keys 11. Further, the concentric array ofprotrusions 22 tends to act as a fulcrum, causing areas outside of thering" of the cluster to rise rather than fall. Further, sinceprotrusions 22 are v preferably shorter than the central protrusion 21,they facilitate closure of the contacts by the central protrusion of theswitch. Force applied to a given key 11 is distributed by protrusion 21until protrusions 22 contact the elastic diaphragm 23. Then, however,the force is concentrated on the central protrusion-21. However, as theforces are increased, the forces are spread out to the stops orprotrusions 22 so that the greater force is distributed over arelatively larger area of the elastic diaphragm 23 by all of the stops22 surrounding the central protrusion 21.

, Rather than employing a central protrusion 21 and a plurality ofcircumferentially spaced secondary protrusions 22 concentricallysurrounding the central protrusion, a modified arrangement for use'witha keyboard with square keys 11 is possible. As shown in FIG. 3, theperipheral protrusions 22 are eliminated and a unitary stop is formed byan endless rib 32 lying inside of the key area of a key 11 (shown inphantom). The central protrusion 21 lies well inside of the isolationarea defined by the individual curved endless rib 32. The rib 32 thusserves as a stop in similar fashion to stops 22 which preventinterference with or from adjacent keys and which absorbs overtravelforces.

However, in such an arrangement, the individual ribs 32 must be formedunder close tolerances at exactly desired locations and the actuatorsheet must be precisely positioned with respect to the other elements ofthe stacked keyboard. Further, since the force for actuation must betransmitted from the key 1 1, through the cover sheet 14, the softbutton 16, ribs 32 must be manufactured with cone-shaped projection 21,ribs 32 must be manufactured with relatively close tolerances to insureproper and uniform force application to the central protrusion 21effecting switch operation. Having thus discussed the prior art, thespecific preferred embodiment of the improvements which comprise theinvention will now be discussed with reference to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning to FIGS. 4 and 5, thekeyboard of the present invention involves, principally, a modifiedactuator sheet illustrated at 120 and being preferably rectangular. Forthe keyboard of FIG. 5, like numerals define like elements to the priorart arrangement of FIGS. 1 through 3. In like fashion the prior artarrangement, sheet 120 is preferably of molded neoprene rubber orsimilar elastomer, having a medium hardness of about 55 to 65 durometersand, in the illustrated arrangement, is approximately one sixteenth inchin thickness and provided with a plurality of clusters of truncated,cone-shaped protrusions 121 and 122 with the central protrusion 121surrounded by four, preferably slightly shorter, protrusions 122circumferentially spaced and concentric with the central protrusion 121.

Unlike the prior art arrangement, an elastomeric actuator sheet 120 hasintegrally molded thereon, on the top or upper surface 100, a pluralityof individual raised pressure pads 102 corresponding in surface area andgenerally in configuration to the visual keying areas of keys 11 on thekeyboard. While the raised pressure pads 102 are shown as being square,they may be irregular, rectangular or circular in form, depending ofcourse upon the configuration and location of the individual keys 11 ofthe keyboard. The contact surface 104 of each of the raised pressurepads lies in contact with a soft button 16 of the integral pad 18 and inalignment with its respective key 11. Thus, under this arrangement,there is even pressure distribution over the pertinent contact area, inparticular that area covering. the series of projections 121-122. Withthe raised pressure pad 102 in contact with the major portion of thesoft button 16, the soft button need not have the tolerance requirementof the prior art design. A variation in button tolerance will not befelt by any change in switch actuating pressure due to the presence ofthe raised pressure pad 102, which assures a more constant pressurepattern for making the switches.

On the underside of the actuator sheet 120 there is provided a pluralityof intersecting, straight-line ribs 132 of rectangular cross sectionwhich are also integrally molded into the actuator sheet 120. The raisedribs 132 define rectangular isolation zones 106 within which, of course,are carried the protrusions 121422. The raised ribs 132 lie outside thearea of pressure pads 102 on the opposite side of the actuator sheet.The raised ribs 132, due to their intersections, define a regular matrixof rectangular isolation zones corresponding directly with the array ofrectangular keys 11 of the keyboard 10. Further, since the straightline, evenly spaced raised ribs 132 contact major portions of the entireunderlying elastic diaphragm sheet 123, the actuator lies flat andparallel with the elastic diaphragm sheet 123, thereby insuring uniformtravel for each key being depressed and more uniform alignment of theactuator projection 121, achieving switching of contacts 124 and 127 foreach switch location.

It is apparent from the above description that the actuator constitutesa more reliable, better balanced pressure actuator than the previouslyused actuator illustrated in FIGS. 1 through 3, inclusive.

What is claimed is:

1. In an elastic diaphragm switch assembly including; an array ofdeflectable diaphragm switch contacts and an elastomeric sheet overlyingsaid array of contacts with a plurality of projections dependingtherefrom in registration with respective contacts, the improvementcomprising: a series of intersecting ribs carried on the same side ofsaid elastomeric sheet as said projections and defining a matrix ofindividual rectangular isolation zones for said projections, said zonescorresponding in number and position to said array of contacts toeliminate crosstalk and interference problems between adjacent switches.

2. The elastic diaphragm switch assembly as claimed in claim 1 furthercomprising a keyboard, a rigid frame member lying below said keyboardand carrying key position separator openings, soft button means couplingsaid keyboard to said elastomeric sheet through said openings and raisedpressure pads carried by said elastomeric sheet on the surface of saidsheet and facing respective soft button means for each key position toinsure even pressure distribution over the switch contact area of eachzone.

3. The elastic diaphragm switch assembly as claimed in claim 2 whereinsaid series of intersecting ribs and said raised pressure pad areintegrally molded within said elastomeric actuator sheet.

4. The elastic diaphragm switch assembly as claimed in claim 1 whereinsaid intersecting straight-line ribs are of rectangular cross sectionand have a thickness at least as great as the length of said projectionsdepending from the same side of said elastomeric actuator sheet.

5. A keyboard comprising: an elastomeric keyboard means bearing indiciaand defining keys thereon, an elastomeric actuator sheet including aninput surface and an output surface on opposite sides thereof, a rigidframe member having openings therein corresponding to the keys of saidkeyboard member supporting said keyboard means and positionedintermediate of said keyboard means and said actuator sheet, a pluralityof soft elastomeric buttons carried within said frame opening andmechanically coupling said keyboard rality of projections extendingoutwardly of the output means to said actuator sheet, a plurality ofdiaphragm switches in an array corresponding to the keys of saidkeyboard means and having an actuation surface consurface of saidelastomeric actuator sheet for contact with the actuation surface ofrespective diaphragm switches to close contacts of said switchesrelating to specific-key areas of said keyboard means, one of saidprojections being responsive to deflection of said actuator sheet foreffecting closure of said switch contact and a plurality of additionalprojections surrounding said one projection for stopping excessivedeflection of said one projection, and a plurality of intersectingrectangular ribs projecting from the output surface of said elastomericactuator sheet and defining individual rectangular isolation zones forthe projections corresponding to each switch of said array, said seriesof intersecting ribs lying outside of the area defined by said switchcontacts, said actuator sheet projections associated therewith, saidsoft elastomeric button, and said frame openings.

6. The keyboard as claimed in claim 5 wherein the input surface of saidactuator sheet has integrally molded therein raised pressure padscorresponding in surface area and position to the openings within saidframe member and the soft buttons carried thereby in contact with theinput surface of said elastomeric actuator sheet.

"5A3?" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3, 93,775 Dated S t. 26, 1972 Inventor(s) K. A BI'OOICS L L Johnson J iA Mathemrm It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

. Claim .3, Column 5, line 6, change "pad" to --pads--;

Claim 3, Column 5, line 7, delete "actuator";

Claim 1, Column 5, line 9, delete "straight-line";

Claim l, Column 5, line 12, delete "actuator-"5' Claim 5, Column 5, line19, after "keyboard" delete "member" and insert therefor --means for--;

Claim 5, Column 5, line 22, after "frame" insert --member--;

Claim 5, Column 6, line 7, delete "said switch contact" and inserttherefor --a switch contact of a respective diaphragm switch--;

Claim 5, Column 6, line 1 1, delete "series" and insert therefor--plurality--;

Claim 5, Column 6, line 18, delete "button" and insert therefor--buttons--;

Claim 5, Column 6, line 19, after "frame" insert --member--.

Signed and sealed this 13th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK J Attesting Officer Commissionerof Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3, 93,775 Dated Sgm. 26, 1972 Inventor(s) K. A. BIOOkS, L. L.Johnson. J. A- Mathe snn It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Claim 3, Column 5, line 6, change "pad" to --pads-;

Claim 3, Column 5, line 7, delete "actuator";

Claim u, Column 5, line 9, delete "straight-line";

Claim 4, Column 5, line 12, delete "actuator";

Claim 5, Column 5, line 19, after "keyboard" delete "member" and inserttherefor --means for--;

Claim 5, Column 5, line 22, after "frame" insert --member--;

Claim 5, Column 6, line 7, delete "said switch contact" and inserttherefor --a switch contact of a respective diaphragm switch-;

Claim 5, Column 6, line l l, delete "series" and insert therefor--plurality--;

Claim 5, Column 6, line 18, delete "button" and insert therefor--buttons--;

Claim 5, Column 6, line 19, after "frame" insert --member--.

Signed and sealed this 13th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK J Attesting Officer Commissionerof Patents

1. In an elastic diaphragm switch assembly including; an array ofdeflectable diaphragm switch contacts and an elastomeric sheet overlyingsaid array of contacts with a plurality of projections dependingtherefrom in registration with respective contacts, the improvementcomprising: a series of intersecting ribs carried on the same side ofsaid elastomeric sheet as said projections and defining a matrix ofindividual rectangular isolation zones for said projections, said zonescorresponding in number and position to said array of contacts toeliminate crosstalk and interference problems between adjacent switches.2. The elastic diaphragm switch assembly as claimed in claim 1 furthercomprising a keyboard, a rigid frame member lying below said keyboardand carrying key position separator openings, soft button means couplingsaid keyboard to said elastomeric sheet through said openings and raisedpressure pads carried by said elastomeric sheet on the surface of saidsheet and facing respective soft button means for each key position toinsure even pressure distribution over the switch contact area of eachzone.
 3. The elastic diaphragm switch assembly as claimed in claim 2wherein said series of intersecting ribs and said raised pressure padare integrally molded within said elastomeric actuator sheet.
 4. Theelastic diaphragm switch assembly as claimed in claim 1 wherein saidintersecting straight-line ribs are of rectangular cross section andhave a thickness at least as great as the length of said projectionsdepending from the same side of said elastomeric actuator sheet.
 5. Akeyboard comprising: an elastomeric keyboard means bearing indicia anddefining keys thereon, an elastomeric actuator sheet including an inputsurface and an output surface on opposite sides thereof, a rigid framemember having openings therein corresponding to the keys of saidkeyboard member supporting said keyboard means and positionedintermediate of said keyboard means and said actuator sheet, a pluralityof soft elastomeric buttons carried within said frame opening andmechanically coupling said keyboard means to said actuator sheet, aplurality of diaphragm switches in an array corresponding to the keys ofsaid keyboard means and hAving an actuation surface confronting theoutput surface of said actuator sheet, a plurality of projectionsextending outwardly of the output surface of said elastomeric actuatorsheet for contact with the actuation surface of respective diaphragmswitches to close contacts of said switches relating to specific keyareas of said keyboard means, one of said projections being responsiveto deflection of said actuator sheet for effecting closure of saidswitch contact and a plurality of additional projections surroundingsaid one projection for stopping excessive deflection of said oneprojection, and a plurality of intersecting rectangular ribs projectingfrom the output surface of said elastomeric actuator sheet and definingindividual rectangular isolation zones for the projections correspondingto each switch of said array, said series of intersecting ribs lyingoutside of the area defined by said switch contacts, said actuator sheetprojections associated therewith, said soft elastomeric button, and saidframe openings.
 6. The keyboard as claimed in claim 5 wherein the inputsurface of said actuator sheet has integrally molded therein raisedpressure pads corresponding in surface area and position to the openingswithin said frame member and the soft buttons carried thereby in contactwith the input surface of said elastomeric actuator sheet.